On the frozen landscape of Antarctica, emperor penguins huddle together to shield against cold, windy, and harsh conditions. This lets the penguins share warmth and conserve energy during extended times between forages and during breeding.

Now scientists have used advances in remote sensing techniques to observe the evolution of an emperor penguin huddle at Atka Bay in eastern Antarctica. Their study revealed the primary trigger that prompts the birds to huddle and reaffirmed the main purpose of the groupings.

Huddle locations often lie kilometers from the nearest permanent research station amid extremely cold (−50°C) and windy (150-kilometer-per-hour) conditions. They also tend to migrate around.

“We can go online anytime and instantly see what is happening in the [emperor penguin] colony.”These factors “have made it very challenging to get information from over there,” according to Céline Le Bohec, an ecologist at the Centre National de la Recherche Scientifique in Paris, France, and the Centre Scientifique de Monaco. However, thanks to remote sensing observatories established by researchers in recent years, especially ones with instruments linked to the Internet, “we can go online anytime and instantly see what is happening in the [emperor penguin] colony,” she said in a press release.

Huddling for Warmth

During May 2014, sensors at the remotely operated Single Penguin Observation and Tracking (SPOT) observatory monitored huddles’ shapes and total areas of coverage and estimated the number of individual penguins within each huddle. Additional SPOT instruments simultaneously recorded the local wind speed, ambient temperature, solar radiation, and relative humidity.

By comparing the local weather conditions to the penguins’ huddling habits, the researchers found that during a typical month, the penguins were more likely to huddle when a windchill-like parameter—which they call the phase transition temperature—decreased to −48.2°C. The penguins’ response to the changing weather conditions during 1 day can be seen in this time-lapse video from 8 May 2014.

Penguins as Proxies

The transition temperature, which combines four meteorological parameters into a single metric measured in degrees, can serve as a proxy for the penguins’ foraging success, according to the team. So if the penguins for some reason began to huddle at warmer temperatures, scientists would know that they likely had smaller energy reserves from food to keep them warm.

The findings agree with the well-established idea that the penguins huddle primarily for warmth and not for protection against predators and reconcile lingering questions about the main environmental trigger for huddling. The researchers published the first results from the study in early May in the Journal of Physics D: Applied Physics.

With ongoing, near-continuous data beginning in 2013, the researchers noted that the penguins’ huddle behavior can track how the Antarctic biome is changing in response to global warming and better inform conservation efforts.

“It’s important to know which colonies are going to be the…most affected by climate change,” said coauthor Daniel Zitterbart of the Woods Hole Oceanographic Institution in Woods Hole, Mass. So if it looks like penguins in a certain colony could withstand future climate-related changes, “conservation measures like marine protected areas can be established to better protect them,” he said.

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